1. Field of the Invention
The present invention relates generally to systems and methods for ion separation in an aqueous solution. In particular, the present invention relates to systems and methods for using electrical forces to remove impurities from an aqueous solution.
2. Background Information
Ion-exchange is an exchange of ions between two electrolytes or between an electrolyte solution and a complex. The term is commonly used to denote the processes of purification, separation, and decontamination of aqueous and other ion-containing solutions with solid polymeric or mineralic ‘ion-exchangers’.
Typical ion-exchangers are ion-exchange resins (functionalized porous or gel polymer), zeolites, montmorillonite, clay, and soil humus. Ion-exchangers are either cation exchangers that exchange positively charged ions (cations) or anion exchangers that exchange negatively charged ions (anions). There are also amphoteric exchangers that are able to exchange both cations and anions simultaneously. However, the simultaneous exchange of cations and anions can be more efficiently performed in mixed beds that contain a mixture of anion and cation exchange resins, or by passing the treated solution through several different ion-exchange materials.
Ion-exchangers can be unselective or have binding preferences for certain ions or classes of ions, depending on their chemical structure. This may be dependent on the size of the ions, their charge, or their structure. Typical examples of ions that can bind to ion-exchangers are H+ (proton) and OH− (hydroxide), single-charged monatomic ions like Na+, K+, and Cl−, double-charged monatomic ions like Ca2+ and Mg2+, polyatomic inorganic ions like SO42− and PO43−, organic bases, usually molecules containing the amino functional group —NR2H+, organic acids, often molecules containing —COO− (carboxylic acid) functional groups, and biomolecules that are capable of ionization, such as amino acids, peptides and proteins.
Ion-exchange is widely used in the food & beverage, hydrometallurgical, metals finishing, chemical & petrochemical, pharmaceutical, sugar & sweeteners, ground & potable water, nuclear, softening & industrial water, semiconductor, power, and a host of other industries. For example, ion separation is commonly used to prepare high purity water for power engineering, electronic and nuclear industries. Ion-exchange is a method widely used in household (laundry detergents and water filters) to produce soft water. This is accomplished by exchanging calcium Ca2+ and magnesium Mg2+ cations against Na+ or H+ cations.
Industrial and analytical chromatography is a further area where ion-exchange is used. Ion-exchange chromatography is a chromatographical method that is widely used for chemical analysis and separation of ions. For example, in biochemistry it is widely used to separate charged molecules such as proteins. An important area of the application is extraction and purification of biologically produced substances such as proteins (amino acids) and DNA/RNA. Ion-exchange processes are also used to separate and purify metals, including separating uranium from plutonium and other actinides, including thorium, and lanthanum, neodymium, ytterbium, samarium, lutetium, from each other and the other lanthanides.
The ion-exchange process generally requires that the desired ligand or constituent be bound to an ion-exchange resin or gel which may result in the ligand undergoing an undesirable physical transformation. For example, when using ion-exchangers to separate proteins, the proteins are often required to partially unfold or denature upon binding with the ion-exchange material. Binding between the ligand and the ion-exchange material further requires that the ligand be partially removed from its aqueous environment. Once eluted from the ion-exchange material, the protein must refold. It is uncertain whether the ligand will refold correctly upon being eluted.
Thus, although methods currently exist for separating ions from aqueous solutions, challenges still exist. Accordingly, it would be an improvement in the art to augment or even replace current techniques with other techniques.